The present invention relates to the technical field of combustion chambers for turbine engines. It is aimed in particular at a combustion chamber and at a method of producing the chamber endwall. It is finally aimed at a turbine engine equipped with such a combustion chamber.
Throughout the following, the terms “axial”, “radial” and “transverse” correspond respectively to an axial direction, a radial direction and a transverse plane of the turbine engine respectively, and the terms “upstream” and “downstream” correspond to the direction of gas flow in the turbine engine respectively.
A conventional combustion chamber is illustrated in FIG. 6, which is an axial section showing one half of the combustion chamber, the other half thereof being derived by symmetry with respect to the axis of the turbine engine (not shown). The combustion chamber 110 is contained within a diffusion chamber 130 which is an annular space defined between an external casing 132 and an internal casing 134, into which space is introduced a compressed oxidant originating upstream from a compressor (not shown) by way of an annular diffusion duct 136.
This conventional combustion chamber 110 comprises an external wall 112 and an internal wall 114 which are coaxial and substantially conical and which widen out from upstream to downstream with a cone angle α substantially ranging between 10 and 12 degrees. The external 112 and internal 114 walls of the combustion chamber 110 are connected to one another toward the upstream end of the combustion chamber by a chamber endwall 116.
The chamber endwall 116 is a frustoconical annular component which extends between two substantially transverse planes while widening out from downstream to upstream. The chamber endwall 116 is connected to each of the two external 112 and internal 114 walls of the combustion chamber 110. Owing to the small inclination of the combustion chamber 110, the chamber endwall 116 has a small conical taper. It is provided with injection openings 118 through which pass injection systems 120 which introduce fuel at the upstream end of the combustion chamber 110 where the combustion reactions take place.
These combustion reactions have the effect of radiating heat from downstream to upstream in the direction of the chamber endwall 116. In order to prevent this chamber endwall 116 from being damaged due to the heat, thermal protection shields, also termed deflectors 122, are provided. These deflectors 122 are substantially flat plates which are fastened by brazing to the chamber endwall 116. They are cooled by means of jets of cooling air which enter the combustion chamber 110 through cooling orifices 124 drilled in the chamber endwall 116. These jets of air, which flow from upstream to downstream, are guided by chamber fairings 126, cross the chamber endwall 116 through the cooling orifices, and impact on an upstream face of the deflectors 122.
In turbine engine designs in which the outlet of the high-pressure compressor is centrifugal, the mean diameter at the high-pressure compressor outlet is greater than the mean diameter at the high-pressure turbine inlet. The external and internal walls of the combustion chamber are therefore inclined by widening out from downstream to upstream, and not from upstream to downstream as with the conventional combustion chambers described above, with a cone angle substantially ranging between 25 and 35 degrees.
Such a large inclination of the combustion chamber has repercussions on the conical taper of the chamber endwall and on the position of the deflectors with respect to the chamber endwall. Such a combustion chamber is partially illustrated in FIG. 7, in axial section. This figure shows an axial direction 100 parallel to the axis of the turbine engine, the main direction 200 of the combustion chamber 110, and the angle α between these two axes 100, 200. Owing to the large inclination of the combustion chamber 110, the chamber endwall 116 has a larger conical taper than a conventional combustion chamber endwall. That affects the distance D between the chamber endwall with a large conical taper and the planar deflectors. In the plane of the axial section shown in FIG. 7, the distance D between the chamber endwall 116 and the deflectors 122 appears to be constant. However, as illustrated in FIG. 8, which is a section on the plane VIII-VIII in FIG. 7, this distance D diminishes as it extends over a circumferential generatrix of the chamber endwall 116, to a point such that the chamber endwall 116 and the deflectors 122 come into contact. Such a contact between these components is detrimental to a correct assembly of the deflectors in the combustion chamber. As a result, the cooling of the chamber endwall 116 by the deflectors 122 is not performed correctly.